Myocarditis

Definition

Alternative Names

Inflammation - heart muscle

Causes

Myocarditis is an uncommon disorder. Most of the time, it is caused by an infection that reaches the heart.

When you have an infection, your immune system produces special cells to fight off disease. If the infection affects your heart, the disease-fighting cells enter the heart. However, the chemicals made by these cells can also damage the heart muscle. As a result, the heart can become thick, swollen, and weak.

Many cases are caused by a virus that reaches the heart. These can include the influenza (flu) virus, coxsackievirus, parovirus, cytomegalovirus, adenovirus, and others.

It may also be caused by bacterial infections such as Lyme disease, streptococcus, mycoplasma, and chlamydia.

Other causes of myocarditis include:

Reactions to certain medicines, such as certain chemotherapy drugs

Exposure to chemicals in the environment, such as heavy metals

Infections due to fungus or parasites

Radiation

Autoimmune disorders that cause inflammation throughout the body

Sometimes the exact cause may not be discovered.

Symptoms

There may be no symptoms. Symptoms may be similar to the flu. If symptoms occur, they may include:

Exams and Tests

Myocarditis can be hard to diagnose because the signs and symptoms often mimic those of other heart and lung diseases, or a bad case of the flu.

The health care provider may hear a rapid heartbeat or abnormal heart sounds while listening to the child's chest with a stethoscope. A physical exam may detect fluid in the lungs and swelling in the legs in older children.

can show enlargement (swelling) of the heart. If the provider suspects myocarditis based on the exam and chest x-ray, an may also be done to help make the diagnosis.

Other tests that may be needed include:

Blood cultures to check for infection

Blood tests to look for antibodies against viruses or the heart muscle itself

Blood tests to check liver and kidney function

Complete blood count

Heart biopsy (the most accurate way to confirm the diagnosis, but not always needed)

Special tests to check for the presence of viruses in the blood (viral PCR)

Treatment

Treatment is aimed at the cause of the problem, and may involve:

Antibiotics to fight bacterial infection

Medicines called steroids to reduce swelling

Intravenous immunoglobulin (IVIG), a medicine made of substances (called antibodies) that the body produces to fight infection, to control the inflammatory process

Diuretics to remove excess water from the body

Low-salt diet

Reduced activity

If the heart muscle is weak, your provider will prescribe medicines to treat heart failure. Abnormal heart rhythms may require the use of other medicines. You may also need a device such as a pacemaker, or implantable cardioverter-defibrillator's to correct an irregular heartbeat. If a blood clot is in the heart chamber, you will also receive blood thinning medicine.

Rarely, a heart transplant may be needed if the heart muscle has become very weak or you have other health problems.

Outlook (Prognosis)

The outcome can vary, depending on the cause of the problem and a person's overall health. Some people may recover completely. Others may have lasting heart failure.

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